1. Field of the Invention
The present invention relates generally to traffic control systems and, more specifically, to a control system that controls traffic flow at signalized intersections by changing lane usage in real time in response to changing traffic patterns.
2. Description of the Related Art
For as long as there have been traffic signals there have been traffic jams. Every motorist has encountered the frustrations associated with long delays at traffic intersections due to un-synchronized traffic signals. A major contributor to these delays are situations wherein during the morning rush hour, in one direction traffic is backed up for miles, and in the opposite direction traffic is very light. During the evening rush hour the pattern reverses itself. While the number of overall lanes for each road may be adequate, an inadequate number of through lanes or left/right turn lanes in the busy direction is a major contributor to traffic congestion on many roads.
In an effort to minimize traffic congestion caused by the above described situation, traffic engineers have attempted to improve the efficiency of signalized traffic intersections by: changing signal and detection hardware and software; improving signs and markings to better inform motorists; and improving traffic flow by making changes to traffic regulations (e.g., right turn on red). In addition, traffic engineers have installed electronic, overhead, lane usage signs that increase or decrease the number of usable lanes in a given direction during certain time periods. For example, during morning rush hour the electronic signs may allow four eastbound lanes and only two westbound lanes. Conversely, during the evening rush hour the electronic signs will allow only two eastbound lanes while allowing four westbound lanes. This type of control system, however, is preprogrammed such that at certain time periods on certain days (e.g., weekdays) the system will allow a preset number of traffic lanes in each direction. There are no provisions for real time analysis of traffic flow and real time automatic adaptation of lane control in response to changes in traffic flow. Consequentially, the system does little to alleviate traffic congestion during off peak hours or traffic congestion due to unforeseen circumstances.
Several traffic control systems have been described in the patent literature. U.S. Pat. No. 2,260,051 issued to Pardee on Jun. 24, 1940, shows a system of traffic control wherein barriers are raised and lowered automatically to vary the effective width of a roadway. U.S. Pat. No. 2,287,685 issued to Jelinek on Jun. 23, 1942, discloses lighted curbs that raise and lower to divide traffic depending on the rush hour. U.S. Pat. No. 3,334,554 issued to Adams on Aug. 8, 1967, discloses a temporary, traffic directing marker. U.S. Pat. No. 3,593,261 issued to Dominguez on Jul. 13, 1971, shows a traffic lane control apparatus with illuminated divider strips, that responds to the density and direction of traffic to control lane usage. U.S. Pat. No. 3,257,552 issued to Converso on Jun. 21, 1966, U.S. Pat. No. 5,074,706 issued to Paulos on Dec. 24, 1991, Canadian Patent No. 954,101 issued on Sep. 3, 1974, and British Patent Application No. 2,263,298 published Jul. 21, 1993, all teach methods of mounting a lighted indicator on pavement. These prior art devices do not teach a traffic intersection control system having illuminated lane markers, overhead traffic control signs, and the ability to change the lane geometry of an intersection based on real time analysis of traffic flow.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.